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TMS320F28335: I'm curious about how CSM works

Han SeungJae
Intellectual 980 points
Part Number: TMS320F28335


Hello,

I am a student studying the Code Security module.

If i look at the 1.4 Functional Block Diagram in the related document[4p]( http://www.ti.com/lit/ds/symlink/tms320f28335.pdf ), i can see that yellow areas, L0-L3 SARAM, OTP and Flash areas are protected by CSM.
However, the arrow on the CSM points only to the L0-L3 parts except OTP and Flash.

Why doesn't CSM point the arrow to the Flash area? It only refers to the Flash Wrapper and I wonder if it means protecting the Flash and OTP areas.

And I'm curious about the role of Pump and Flash Wrapper. I'm curious what it's for and how it connects to the CSM.

It seems that Flash Wrapper operates CSM through PSWD. Does Flash Wrapper have 128-bit password (0x33 FFF8 ~ 0x33 FFFF)?

Also, is Emulation Code Security logic (ECSL) a logic that always operates independently of CSM?

I would appreciate a kind explanation for me.

Regrads,

Han

  • 0
    TI__Guru* 95315 points

    Why doesn't CSM point the arrow to the Flash area?

    This is just a simplified block diagram that is representative of the design. Its purpose is not to show every connection. 

    It only refers to the Flash Wrapper and I wonder if it means protecting the Flash and OTP areas.

    Yes, it does protect flash and OTP. 

    And I'm curious about the role of Pump and Flash Wrapper. I'm curious what it's for and how it connects to the CSM.

    The pump generates the voltage needed for reading and programming. Flash wrapper is like the interface between the CPU and the flash array. How it connects to the CPU is proprietary design information and cannot be shared.

    It seems that Flash Wrapper operates CSM through PSWD. Does Flash Wrapper have 128-bit password (0x33 FFF8 ~ 0x33 FFFF)?

    The passwords are stored in the flash array.

    Also, is Emulation Code Security logic (ECSL) a logic that always operates independently of CSM?

    ECSL works in conjunction with the CSM.